The use of an electric motor to drive a fluid pump is well known. For example, such motor/pump combinations are often used to circulate the water in a swimming pool or to supply pressure for the water jets in a hot-tub or spa. Electric motors produce heat during operation roughly in proportion to the horsepower rating of the motor. This heat energy is typically dissipated by the motor casing or other cooling means and wasted.
Various methods of cooling electric motors, including the use of liquid filled heat exchangers, are known. However, these systems typically require external means for circulating the cooling fluid through the heat exchanger, e.g. a coolant pump, and for cooling the fluid after it exits the heat exchanger. Also, the cooling fluid is typically not the same fluid as that being moved by the main pump.
It is often desirable to heat the particular fluid being pumped to maintain a relatively high fluid temperature in the particular system. Heating the water in spas and swimming pools, for example, is usually accomplished using heaters made especially for that purpose. Such heaters are typically expensive both to purchase and to operate.
It would, therefore, be desirable to provide a simple and inexpensive device for recovering the heat energy generated by an electric pump motor thereby warming the fluid being pumped.